From WO 2008/071362 A1 a generic heat exchanger, for example in the manner of a cooler, is known, comprising a block for conducting the two fluids separately and so as to exchange heat, said block having a number of flat tubes through which the first fluid flows and which comprise a narrow tube side and a wide tube side. The flat tubes terminate respectively on the longitudinal end side in a base of a box, wherein the flat tubes are guided into the box via corresponding through-openings in the base. Each of the through-openings in the base has here a raised edge which surrounds the corresponding flat tube, wherein the wide edge sides are usually higher than the narrow edge sides and transition into one another via a corresponding inclination.
A disadvantage in the known heat exchanger, however, is that owing to the high temperature differences, stresses occur in the region of the inclination between the wide edge side and the narrow edge side on the base of the heat exchanger, which have a disadvantageous effect on the service life of the heat exchanger.